小麦替代部分玉米对高原型藏羊肌纤维类型分布和肉质性状的影响

Effects of a partial substitution of corn with wheat on the distribution of muscle fiber types and meat quality traits in plateau-type Tibetan sheep

为阐明小麦(Triticum aestivum)替代10%玉米(Zea mays)对高原型藏羊(Ovis aries)肌纤维类型及其肌肉脂肪酸与抗氧化功能的影响,选取初始体重相近[(19.35±2.18)kg]且发育良好的2~3月龄高原型藏羊公羔60只,随机分为两组(各组设置5个重复),即玉米组精料补充料为玉米(对照CG),小麦组饲喂小麦粉料替代精料中10%玉米(WG)。试验分预试期10 d和正试期90 d。结果表明:1)与CG组相比,WG组的Ⅰ型肌纤维数量极显著下降(P<0.01),而Ⅱ型肌纤维数量则呈相反趋势(P<0.01);2)WG组的MyHCⅠ基因mRNA相对表达量极显著高于CG组(P<0.01),而MyHCⅡb基因mRNA相对表达量亦呈相反趋势(P<0.01);3)CG组的肌肉二十二碳酸(C22:0)显著高于WG组(P<0.05),CG组的肌肉二十二碳三烯酸(C22:3)显著低于WG组(P<0.05);4)两组的肌肉总抗氧化能力(T-AOC)、丙二醛(MDA)含量,谷胱甘肽过氧化物酶(GSH-Px)、过氧化氢酶(CAT)及超氧化物歧化酶(SOD)活性差异均不显著(P>0.05)。研究结果表明,以10%小麦替代部分玉米对高原型藏羊的肉质具有一定改善作用。

In this study,we sought to determine the effects of substituting 10%of dietary maize with wheat flour on muscle fiber types,fatty acid contents,and antioxidant properties in plateau-type Tibetan sheep(Ovis aries).Sixty 2~3th-old plateau Tibetan lambs with similar initial body weight[(19.35±2.18)kg]and good development were randomly divided into one of two groups(with 5 repetitions per group),namely,a corn group(CG:fed pure corn as a concentrate)and a wheat group(WG:10%of the corn concentrate substituted with wheat).The results revealed that compared with the CG group lambs,there were significantly fewer typeⅠmuscle fibers in the WG group lambs(P<0.01),whereas the number of typeⅡmuscle fibers showed the opposite trend(P<0.01).In addition,the relative mRNA expression of the MyHCI gene in WG group lambs was significantly higher than that in the CG group lambs(P<0.01),whereas the relative expression of the MyHC IIb gene.The relative expression of docosanoic acid(C22:0)in CG group lambs was significantly higher than that in the WG group lambs(P<0.05),whereas the relative expression of docosatrienoic acid(C22:3)in the CG group was significantly lower than that in the WG group(P<0.05).Moreover,the two groups were found to show opposite trends with respect to total antioxidant capacity,malondialdehyde content,and glutathione peroxidase activity(P<0.01).However,we detected no significant difference between the two groups with respect to the activities of the enzymes catalase and superoxide dismutase(P>0.05).The findings of this study indicate that replacing 10%of dietary corn with wheat contributes to a certain improvement in the quality of plateau Tibetan sheep meat.